I think this sounds awesome, but I’d suggest reconsidering top-down and go bottom-up. If you look at endless scroller games and games like Guitar Hero, the “what’s coming” flows from the top of the screen … often it’s a 3D from the horizon effect, but put on paper it would be best to have the flow from the bottom to the top. Also, it’s just as easy to scroll from the bottom to the top of a document or page when looking at a computer screen. Of course, it would be testable to see if top-to-bottom or bottom-to-top would be better.